A major fundraiser for Susan G Komen for the Cure, the breast cancer advocacy group at the centre of a row over its funding cut to Planned Parenthood, has called for the organisation to "clean house" at the top, starting with the resignation of its founder Nancy Brinker.

Eve Ellis, a former board member of affiliate group Komen New York City, said she does not believe Brinker's claims that the cuts were not politically motivated and, as a result, no longer trusts Komen as an organisation. A passionate supporter and board member of six years standing who has raised $250,000 for Komen NYC, Ellis has cut all ties to the group.

She describes Komen's moves to try to restore public confidence – including a U-turn on the funding cut and the resignation of vice-president, Karen Handel, on Tuesday – as "not enough".

Handel resigned after a week of fierce criticism over the decision to strip Planned Parenthood of funding but disputed she was the driving force behind it.

Ellis is the latest in a growing number of prominent individuals associated with Komen to cut their ties with the group following the furious backlash against it.

The controversy over America's largest breast cancer advocacy group – and one that is highly revered – has refused to abate, despite Komen's crisis management. At the heart of the storm is that few believe the organisation's continued insistence that the decision to defund Planned Parenthood was apolitical.

In a letter sent to family and friends on Monday, before Handel's resignation, Ellis called for Handel, Brinker and all nine board members to go, so that "I and the millions of people who have walked and talked for Komen can trust again."

Speaking to the Guardian on Wednesday, Ellis, a philanthropy and wealth advisor, said of Handel's leaving: "Even in her resignation, she says that is wasn't just her decision. Others have said it was. It doesn't matter. It was approved by the board. Whether it came from the CEO or the board or a certain employee, they all were complicit."

Brinker, who set up the organisation as a vow to her dying sister to work to end breast cancer in the US, has apologised for the debacle and has personally insisted that the decision to end funding to Planned Parenthood was not politically motivated.

In Ellis's letter [reproduced here with Ellis's permission], a response to family and friends asking her whether the organisation could be trusted, Ellis refers to her disappointment even as Brinker reversed the funding decision. "Brinker's words struck me as vague and hollow – no future commitment to Planned Parenthood and no specific apology to the low-income women who would have become the collateral damage from the defunding," Ellis wrote.

"I also don't believe Brinker and her board when she claims that Komen's decision wasn't political."

She notes that Brinker was a former ambassador under George Bush, and Cecile Richards, the head of Planned Parenthood, is the daughter of a Bush family opponent, late Texas governor Ann Richards.

"Take some truth serum, Nancy Brinker, I found myself thinking," she wrote in her letter, which refers to reports that Brinker told affiliates that Ari Fleischer, the former White House press secretary in the Bush administration, would be available to advise them on crisis communication. Ellis asked: "How did the Komen action originate? Is women's health a political game, Nancy Brinker?"

Ellis goes on: "A clean house would enable Komen to carry on its much-needed, admirable work without the baggage of being the organisation that had actually deliberated on and subsequently made the heartless decision to defund Planned Parenthood and to endanger the heath of thousands of women. When we have a clean house, we should get answers to how this happened, and a clear refocus that Komen stands for all women's health."

In its original decision to defund Planned Parenthood last week, Komen cited an investigation backed by anti-abortion groups and launched by Republican congressman, Cliff Stearns, to determine if Planned Parenthood improperly spent public money on abortions. Planned Parenthood says taxpayer money is strictly separated.

Komen reversed course after its decision created a three-day storm of criticism. Members of Congress and Komen affiliates accused the group's national leadership of bending to pressure from anti-abortion activists. Brinker denied the accusation.

On Tuesday, following her resignation, Handel, a pro-life advocate who ran a failed campaign for Georgia governor, appeared on Fox news in an interview in which she appeared to blame Planned Parenthood for the row.

"What was unleashed over this past week was a vicious attack against a great organization," Handel said. "I would think all of us should be saddened that an outside organization should put this kind of pressure on another organisation."

She added: "The last time I checked, private non-profit organizations have a right and a responsibility to be able to set the highest standards and criteria on their own without interference, let alone the level of vicious attacks and coercion that has occurred by Planned Parenthood. It's simply outrageous."

• This article was amended on 9 February 2012. The original said that Karen Handel ran a failed campaign for Texas governor. This has been corrected.